It is the first time Ukranian authorities - fighting to quell a pro-Russia separatist movement in the east of the country - has directly accused Russia of using air power in the war.

In a previous attack on a military transporter, which Kiev said was launched from Russia, the government was unable to specify whether it came from landbased missiles or airborne.

This time the Ukranians are positive but Russia's defence ministry called the accusation "absurd".

The SU-25 fighter plane was allegedly brought down on Wednesday night near Amvrosiyivka, about 15 km from the Russian border.

According to sources, It was hit by rockets as it wheeled away from the border.

A spokesman for the Ukranian Defence Ministry said: "It is likely that this was carried out by air-to-air rockets from the Russian airforce which were patrolling the border in a pair."

The pilot safely ejected and was rescued by Ukranian forces.

The downing came against a background of increasingly strident charges of direct Russian involvement in the three and a half month conflict in which the pro-Western government in Kiev is fighting to put down.

Moscow denies orchestrating the rebellion which wants closer ties with Russia rather than Europe.

Five Ukrainian servicemen had been killed in the past few days which brings to more than 270 the number killed since the government launched its "anti-terrorist" operation in April to crush the rebels.